[Instruction] Remove setProfWeight()

Remove the function Instruction::setProfWeight() and make
use of Instruction::copyMetadata(.., {LLVMContext::MD_prof}).
This is correct for all use cases of setProfWeight() as it
is applied to CallBase instructions only.
This change results in prof metadata copied intact even if
the source has "VP". The old pair of calls
extractProfTotalWeight() + setProfWeight() resulted in
setting branch_weights if the source had "VP" data.

Reviewers: yamauchi, davidxl
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D80987

llvm/include/llvm/IR/Instruction.h

@@ -332,9 +332,6 @@ public:
   /// Returns false if no metadata was found.
   bool extractProfTotalWeight(uint64_t &TotalVal) const;
 
-  /// Sets the branch_weights metadata to \p W for CallInst.
-  void setProfWeight(uint64_t W);
-
   /// Set the debug location information for this instruction.
   void setDebugLoc(DebugLoc Loc) { DbgLoc = std::move(Loc); }
 

llvm/lib/IR/Instruction.cpp

@@ -774,12 +774,3 @@ Instruction *Instruction::clone() const {
   New->copyMetadata(*this);
   return New;
 }
-
-void Instruction::setProfWeight(uint64_t W) {
-  assert(isa<CallBase>(this) &&
-         "Can only set weights for call like instructions");
-  SmallVector<uint32_t, 1> Weights;
-  Weights.push_back(W);
-  MDBuilder MDB(getContext());
-  setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
-}

llvm/lib/Transforms/IPO/ArgumentPromotion.cpp

@@ -336,10 +336,7 @@ doPromotion(Function *F, SmallPtrSetImpl<Argument *> &ArgsToPromote,
     NewCS->setAttributes(
         AttributeList::get(F->getContext(), CallPAL.getFnAttributes(),
                            CallPAL.getRetAttributes(), ArgAttrVec));
-    NewCS->setDebugLoc(CB.getDebugLoc());
-    uint64_t W;
-    if (CB.extractProfTotalWeight(W))
-      NewCS->setProfWeight(W);
+    NewCS->copyMetadata(CB, {LLVMContext::MD_prof, LLVMContext::MD_dbg});
     Args.clear();
     ArgAttrVec.clear();
 

llvm/lib/Transforms/IPO/Attributor.cpp

@@ -1568,11 +1568,8 @@ ChangeStatus Attributor::rewriteFunctionSignatures(
       }
 
       // Copy over various properties and the new attributes.
-      uint64_t W;
-      if (OldCB->extractProfTotalWeight(W))
-        NewCB->setProfWeight(W);
+      NewCB->copyMetadata(*OldCB, {LLVMContext::MD_prof, LLVMContext::MD_dbg});
       NewCB->setCallingConv(OldCB->getCallingConv());
-      NewCB->setDebugLoc(OldCB->getDebugLoc());
       NewCB->takeName(OldCB);
       NewCB->setAttributes(AttributeList::get(
           Ctx, OldCallAttributeList.getFnAttributes(),

llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp

@@ -205,10 +205,7 @@ bool DeadArgumentEliminationPass::DeleteDeadVarargs(Function &Fn) {
     }
     NewCB->setCallingConv(CB->getCallingConv());
     NewCB->setAttributes(PAL);
-    NewCB->setDebugLoc(CB->getDebugLoc());
-    uint64_t W;
-    if (CB->extractProfTotalWeight(W))
-      NewCB->setProfWeight(W);
+    NewCB->copyMetadata(*CB, {LLVMContext::MD_prof, LLVMContext::MD_dbg});
 
     Args.clear();
 
@@ -936,10 +933,7 @@ bool DeadArgumentEliminationPass::RemoveDeadStuffFromFunction(Function *F) {
     }
     NewCB->setCallingConv(CB.getCallingConv());
     NewCB->setAttributes(NewCallPAL);
-    NewCB->setDebugLoc(CB.getDebugLoc());
-    uint64_t W;
-    if (CB.extractProfTotalWeight(W))
-      NewCB->setProfWeight(W);
+    NewCB->copyMetadata(CB, {LLVMContext::MD_prof, LLVMContext::MD_dbg});
     Args.clear();
     ArgAttrVec.clear();
 

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -4955,11 +4955,8 @@ bool InstCombiner::transformConstExprCastCall(CallBase &Call) {
   NewCall->setCallingConv(Call.getCallingConv());
   NewCall->setAttributes(NewCallerPAL);
 
-  // Preserve the weight metadata for the new call instruction. The metadata
-  // is used by SamplePGO to check callsite's hotness.
-  uint64_t W;
-  if (Caller->extractProfTotalWeight(W))
-    NewCall->setProfWeight(W);
+  // Preserve prof metadata if any.
+  NewCall->copyMetadata(*Caller, {LLVMContext::MD_prof});
 
   // Insert a cast of the return type as necessary.
   Instruction *NC = NewCall;

llvm/test/Transforms/InstCombine/cast-call-combine-prof.ll

@@ -32,7 +32,7 @@ lpad:
   unreachable
 }
 
-; CHECK: ![[$PROF]] = !{!"branch_weights", i32 2000}
+; CHECK: ![[$PROF]] = !{!"VP", i32 0, i64 2000, i64 -3913987384944532146, i64 2000}
 !0 = !{!"VP", i32 0, i64 2000, i64 -3913987384944532146, i64 2000}
 
 !llvm.module.flags = !{!1}